Proteus Of The Lakes, Or Fish Lizard Menobrancms, a batrachian of the order amphijmeusta, and of the division of perennibranchiate amphibia, so called because the gills are persistent and external; the order includes also the pro-teus of Europe, the axolotl, ampMuma or Congo snake, menopoma or hellbender, and siren or mud eel of the United States. In the genus menobranchus (Harlan) or necturus (Raf.), the head and mouth are large; the upper jaw with a series of small sharp-pointed teeth, the palate also similarly armed; neck contracted, with three branchial tufts on each side; tail compressed laterally and fringed with a delicate membrane; limbs four, each four-toed; eyes small and without lids; the lips thick and fleshy, the tongue large, entire in front, and movable only at the tip and anterior edges; nostrils small and near the margin of the upper lip; the body elongated and sub-cylindrical, covered with a smooth skin; toes without nails. The best known species is the spotted menobranch (M. maculatus, Barnes), about 12 in. long, of a cinereous dusky gray, with sub-circular darker spots, and a brown stripe extending from the snout over the eyes; it is found in the great lakes of North America and in Lake Champlain, and in the streams opening into them.
In M. lateralis (Say) the color is dusky brown above, with a dark band from the nostrils through the eye and along the sides to the tail, and dirty flesh-colored below; the form is more slender than in the other species; it is found only in the western waters running into the Mississippi, especially if not entirely on its eastern side, from Pennsylvania to Tennessee; it is often called mud puppy. In many specimens kept alive by the writer, some of them for three or four years, obtained from Portage lake, the gills, three on each side, were provided with an immense number of very delicate fringes, deep red when the animal was actively breathing, which were kept waving to and fro in a most graceful manner during respiration; the four limbs, about an inch long, were set almost at a right angle, and the gait was consequently very awkward; the movements executed by the tail are rapid and graceful; the vent is longitudinal; the general aspect of the head is snaky and forbidding, and the Indians erroneously consider them venomous. The specimens above mentioned were very tenacious of life, having been imprisoned under ice half an inch thick every night for three months without apparent injury, and ate nothing for six months except what they obtained from the water.
They often came to the surface to swallow air, which is emitted at the gill opening in bubbles accompanied by a faint squeak. Generally sluggish in their motions, and avoiding the sunlight, they seize living worms eagerly, sucking them down if small at a single gulp, or, if large, by repeated efforts; the sight is not very good, and they rarely snap at their prey unless it touches their mouth. They are sometimes taken on hooks by persons angling for mud fish; they are most active at night, moving rapidly at this time, and often throwing themselves nearly out of water; they feed on insects, worms, small crustaceans, and other living prey. The gills when inactive shrink, and become of a slaty gray color; they are cleansed from impurities by means of the fore feet. When the branchial fringes are lost by accident, the animals do not appear to suffer. They have rudimentary lungs or pulmonary sacs, which assist in respiration by means of the swallowed air; but these are not sufficient of themselves to support life, as the animals die out of water in about four hours; with the cutaneous respiration, active in all amphibians, the air sacs are able to purify the blood.
These animals, having both lungs and gills, though the former are insufficient to prolong life except for an hour or two, probably come as near as any to the fabulous amphibians able to live in water or air. There is no evidence that this animal, like the axolotl, is developed into any terrestrial salamander. (See Axolotl).